Carburetor for internal combustion engines

ABSTRACT

A carburetor for internal combustion engines comprising a housing having a compartment area therein adapted to be in communication with the intake manifold of the engine. The housing also is provided with a cylindrical bore area formed therein below the compartment area. A throttle valve means is slidably mounted in the housing and is adapted to variably restrict the entrance to the compartment area. A carburetor bowl adapted to contain the fuel therein is secured to the throttle valve means and is slidably mounted in the bore of the housing. A spring means is mounted in the bore and yieldably urges the throttle valve upwardly to restrict the entrance to the compartment area. The throttle valve has a combustible fluid passageway formed therein which movably receives a needle valve extending thereinto. The throttle valve has a fluid exit passageway means having one end connected to the passageway of the throttle valve and its other end communicating with the inside of the compartment area. A first conduit communicates with the inside of the fuel bowl and a source of fuel while a second conduit communicates with the compartment area and the inside of the bore. The throttle valve passageway has a tapered valve seat positioned therein which receives an elongated cylindrical end portion of the needle valve to variably restrict the flow of fuel through the throttle valve passageway. Manifold pressure applied to the compartment area causes the throttle valve to move downwardly against the spring means to increase the amount of air entering the entrance area into the compartment area. As the throttle valve moves downwardly, the tapered valve seat moves outwardly from the needle valve to permit a larger volume of fuel to be drawn through the passageway and to be discharged from the fluid exit passageway of the throttle valve. The incoming air mixes with the discharge fuel and the mixture is drawn into the intake manifold. Means is also provided to achieve &#39;&#39;&#39;&#39;fine&#39;&#39;&#39;&#39; adjustment of the carburetor. A modified version of the carburetor is also disclosed and the primary difference of the same with respect to the first embodiment is the location of the fuel bowl with respect to the umbrella portion of the throttle valve.

United States Patent 72] Inventor Edgar D. Jelken RR No. l, Jeffers, Minn. 56145 [21] Appl. No. 828,521 [22] Filed May 28, 1969 [45] Patented Feb. 16, 1971 [54] CARBURETOR FOR INTERNAL COMBUSTION Primary ExaminerTim R. Miles Attorney-Zarley, McKee & Thomte ABSTRACT: A carburetor for internal combustion engines comprising a housing having a compartment area therein adapted to be in communication with the intake manifold of the engine. The housing also is provided with a cylindrical bore area formed therein below the compartment area. A

throttle valve means is slidably mounted in the housing and is adapted to variably restrict the entrance to the compartment area. A carburetor bowl adapted to contain the fuel therein is secured to the throttle valve means and is slidably mounted in the bore of the housing. A spring means is mounted in the bore and yieldably urges the throttle valve upwardly to restrict the entrance to the compartment area. The throttle valve has a combustible fluid passageway formed therein which movably receives a needle valve extending thereinto. The throttle valve has a fluid exit passageway means having one end connected to the passageway of the throttle valve and its other end communicating with the inside of the compartment area. A first conduit communicates with the inside of the fuel bowl and a source of fuel while a second conduit communicates with the compartment area and the inside of the bore. The throttle valve passageway has a tapered valve seat positioned therein which receives an elongated cylindrical end portion of the needle valve to variably restrict the flow of fuel through the throttle valve passageway. Manifold pressure applied to the compartment area causes the throttle valve to move downwardly against the spring means to increase the amount of air entering the entrance area into the compartment area. As the throttle valve moves downwardly, the tapered valve seat moves outwardly from the needle valve to permit a larger volume of fuel to be drawn through the passageway and tobe discharged from the fluid exit passageway of the throttle valve. The incoming air mixes with the discharge fuel and the mixture is drawn into the intake manifold. Means is also provided to achieve fine" adjustment of the carburetor. A modified version of the carburetor is also disclosed and the primary difference of the same with respect to the first embodiment is the location of the fuel bowl with respect to the umbrella portion of the throttle valve.

PATENTED FEB] s [an I SHEET 1 0F 2 CARBURETOR FOR INTERNAL COMBUSTION ENGINES This invention pertains to a carburetor for an internal combustion engine and is generally of the air valve type disclosed in U.S. Pat. Nos. 3,265,374; 3,265,375; 3,273,868; and 3,273,869, all of which issued to Glenn R. Morton. The foregoing patents have been assigned to the inventor of record of the instant application and the invention disclosed herein is an improvement and refinement of the carburetors of the above identified patents.

Generally speaking, all internal combustion engines utilize a carburetor to mix the gasoline and air into an ignitable mixture. The efficiency of the engine necessarily depends on a proper mixture of air and liquid fuel. Conventional carburetors may be adjusted for maximum efficiency for a given engine speed, and/or a given atmospheric pressure.

Therefore, a principal object of this invention is to provide a carburetor that automatically compensates for varying conditions of pressures and temperatures.

A further object of this invention is to provide a carburetor which will balance its throttle position with the outside atmosphere as the engine manifold pressure varies.

A further object of this invention is to provide a carbureto including a fine idle adjustment.

A further object of this invention is to provide a carburetor which provides rapid engine acceleration.

A further object of this invention is to provide a carburetor which will automatically enrich the mixture of gasoline at critical engine stages of operation that require such additional fuel.

A further object of this invention is to provide a carburetor which is more efficient under varying conditions than the heretofore carburetors.

A further object of this invention is to provide a carburetor which is economical of manufacture, durable in use and refined in appearance.

These and other objects will be apparent to those skilled in the art.

This invention consists in the construction, arrangements, and combination of the various parts of the device, whereby the objects contemplated are attained as hereinafter more fully set forth, specifically pointed out in the claims, and illustrated in the accompanying drawings in which:

FIG. I is a top perspective view of the carburetor of this invention;

FIG. 2 is a top view of the carburetor of this invention;

FIG. 3 is an enlarged sectional view as would be seen along lines 3-3 of FIG. 2 with portions thereof cut away to more fully illustrate the invention;

FIG. 4 is an enlarged sectional view as would be seen along lines4-4of FIG. 2; and

FIG. 5 is a vertical longitudinal sectional view of a modified form of the carburetor of this invention.

The carburetor of FIGS. 1-4 is generally referred to by the reference numeral and includes a lower housing 12, upper housing 14 and butterfly valve housing 16. Lower housing 12 is provided with a cylindrical bore 18 formed therein which vertically slidably receives a carburetor bowl 20 therein. As seen in FIG. 3, a throttle valve 22 is secured at its lower end 24 to the bottom 26 of bowl 20 by a nut 28. Spring 30 is positioned between bottom 26 of bowl 20 and the lower end of bore I8 to yieldably urge bowl 20 and throttle valve 22 in an upwardly direction. Bore I8 is also provided with a recess area 32 to accommodate the lower end of the throttle valve 22 when the bowl 20 and throttle valve 22 are in their lowermost position. FIG. 3 illustrates the bowl 20 and throttle valve 22 in their uppermost position.

A conduit or passageway 34 is fonned in lower housing 12 and is in communication with bore 18 below bowl 20 and a compartment area 36 located above bore 18. As seen in FIG. 3, a check ball valve means 38 is provided in a passageway 34. Throttle valve 22 includes a hollow sleeve 40 which vertically slidably embraces a downwardly extending cylinder portion 42 of upper housing 14. Throttle valve 22 also includes an umbrella portion 44 which extends radially outwardly from the lower end of sleeve 40. The upper end of bowl 20 is detachably secured to umbrella portion 44 and has an O-ring 46 positioned therebetween for sealing purposes. The outer upper end of umbrella portion 44 is adapted to move towards and engage the surface 48 formed in upper housing M to variably restrict the entrance to the compartment area 36.

Umbrella portion 44 has a vertical bore 50 formed therein to permit communication between the interior of bowl 20 (above the fuel level) and the atmosphere. Sleeve 40 is provided with a horizontal bore 52 formed therein at the lower end thereof which permits communication between the atmosphere and the interior of sleeve 40 below cylinder portion 42.

The numeral 54 generally designates a plurality of bores or passageways extending from the periphery of umbrella portion has a vertical bore 62 formed therein which permits communication between the lower end of sleeve 40 and bore 56. As illustrated in FIG. 3, needle valve 60 has a stepped down portion 64, the lower end of which is adapted to engage the interior tapered wall surface 66 of a valve seat insert 68 positioned in bore 56. For purposes of description, the numeral 70 will refer to the passageway extending through valve seat insert 68. A plurality of passageways 72 extend outwardly from the lower end of throttle valve 22 to place the lower end of bore 56 in communication with the lower interior area of bowl 20. An O-ring 74 embraces the lower end of throttle valve 22 to prevent fuel leakage from bowl 20.

The numeral 76 designates a split fork float arm having its 7 upper end hinged and its free end riding on top of the float 78 which slidably embraces the tubular portion 80 of the throttle valve 22. The numeral 82 designates a hollow valve housing extending through the umbrella portion 44 and having its lower end communicating with the inside of the bowl 20 above the arm 76. A valve stem 84 is movably mounted in the housing 82 and has its lower end resting on the top of the float arm 76. A conduit means 86 is provided and has one end communicating with the inside of the valve housing 82 and its other .end adapted to be in operative communication with a source of fuel such as gasoline or the like. By the arrangement of parts, when the float 78 drops, due to a shortage of fuel in the carburetor bowl 20, the arm 76 will drop which opens the valve stem 84 and permits fuel to pass from the conduit 86 into the bowl 20. As the bowl fills, the float will rise and close the valve means. The carburetor bowl will be automatically maintained with a constant level of fuel.

Upper housing 14 includes a lower base portion 88 which is secured to the upper end of housing 12 by screws 90. A pair of legs 92 and 94 extend upwardly from base portion 88 and have a hollow cylindrical neck portion 96 extending upwardly therefrom. The area between the legs 92 and 94 define air intake openings generally designated by the reference numeral 98. Collar 100 embraces neck portion 96 and has an opening 102 extending through one side thereof which registers with opening 104 formed in neck portion 96. A pin 106 is rotatably mounted in openings I02 and 104 and is maintained therein by a retaining ring 108. The outer end of pin 106 is connected to a power enrichment lever lloadapted to be connected to a choke wire or the like so that pin 106 may be rotated as desired. The inner end of pin 106 has a cam 112 extending inwardly therefrom which is offset from the center thereof as illustrated in FIG. 4.

An internally threaded cylinder 114 is slidably mounted in bore 116 of neck portion 96 and threadably receives an idle adjustment knob 118 therein. As seen in FIG. 4, cylinder 114 is provided with an opening 120 which rotatably receives the cam 112 so that rotation of pin 106 by the lever will cause cylinder 114 and knob 118 to be vertically moved with respect to bore 116. The upper end of needle valve 60 slidably extends through bore 122 of knob 118 and has a head portion 124 positioned on the top of the same. Spring arm 126 is secured to knob 118 and engages the upper end of head portion 124 to yieldably resist the upward movement of the needle valve 60 with respect thereto.

As illustrated in FIG. 3, the numeral 128 designates the area below cylinder 114 and knob 118 while the numeral 130 designates the area below the lower end of cylinder portion 42. As also illustrated in FIG. 3, base portion 88 has a tapered lower inner end portion 132 which is engaged by the upper outer end of umbrella portion 44 and which provides a fuel-air deflecting surface so that the fuel air will be deflected downwardly and outwardly into the opening 134 and thence into the interior 136 of housing 16. A throttle plate shaft 138 extends through the housing 16 and has a butterfly valve 140 mounted thereon adapted to variably close the entrance to interior 136 upon the operation of the lever 142 connected to shaft 138. interior 136 of housing 16 is operatively connected to the intake manifold of the engine while the lever 142 would be operatively connected to the vehicle accelerator.

A modified form of the carburetor is illustrated in FIG. and is designated by the reference numeral 150 and generally includes a lower housing 152 and an upper housing 154 mounted thereon. Lower housing 152 has a bore 155' provided therein which slidably receives an umbrella portion 156 of throttle valve 158. Throttle valve 158 is yieldably urged upwardly by a spring 160 in the manner illustrated in FIG. 5. Lower housing 152 has a passageway 162 formed therein extending between bore 155 and compartment area 164 and which includes a check valve means! positioned therein. Compartment area 164 is in communication with opening 168 which is variably closed by a butterfly valve means 170 operatively connected to the vehicle accelerator. Opening 168 is in operative communication with the intake manifold of the engme.

Upper housing 154 includes a lower base portion 172 having a tapered deflecting surface 174 provided at the lower and inner end thereof. A pair of legs 176 and 178 extend upwardly from base portion 172 and the open space therebetween defines air intake openings.

The upper end of upper housing 154 is provided with a compartment 180 which serves as a carburetor bowl. Housing 154 also includes an upstanding neck portion 182 which slidably receives the upper end of throttle valve 158. A cap 184 is threadably secured to the upper end of throttle valve 158 and includes a downwardly extending sleeve portion 186 which slidably embraces neck portion 182. Cap 184 has a passageway 188 extending therethrough which is selectively closed by a ball check valve means 190. Throttle valve 158 has a passageway 192 extending therethrough as seen in FIG. 5. The upper end of passageway 192 has a tapered insert or valve seat 194 mounted therein, the interior of which is in communication with passageway 188.

Cover 195 closes the upper end of housing 154 and has a power enrichment lever 196 threadably mounted therein. An idle adjustment knob 198 is adjustably threadably mounted in lever 196 and has a needle valve 200 secured thereto and extending downwardly therethrough. Needle valve 200 is provided with a stepped down end portion 202, the lower end of which variably restricts the passageway 204 in valve seat 194. The rotation of knob 198 with respect to lever 196 changes the relationship of the lower end of the needle valve 200 with respect to the valve seat 94. Lever 196 is operatively connected to a choke wire by a linkage 206 to selectively cause lever 196 to be threadably rotated in cover 195 to effectively raise and lower knob 198 which in turn raises and lowers needle valve 200.

Float 208 slidably embraces cap 184 as illustrated in FIG. 5. Cover 195 has a conduit means 210 extending thereinto which is in communication with a source of fuel. The numeral 211 designates a float arm and valve assembly similar to the assembly illustrated in FIGS. 3 and 4 and operates in the same manner. The numeral 212 designates a metering hole fonned in cap 184 which extends between passageway 188 and acceleration chamber 214.

The operation of the carburetor of FIGS. 1-4 is as follows: The speed of the engine to which the carburetor is attached is controlled by the accelerator which is connected to the butterfly valve to vary the amount of manifold pressure supplied to compartment area 36. The throttle valve 22 is vertically floatable in the carburetor housing but is controlled by engine suction (manifold pressure) and atmospheric pressures working in conjunction with the spring 30. The area above umbrella portion 44 is exposed to the outside atmosphere. When the engine is at idling speed, the manifold pressure will exist in the compartment area 36, passageway 34 and bore 18 since the suction will open the check ball valve means 38. The manifold pressure or suction in bore 18 causes throttle valve 22 to be moved downwardly from the position illustrated in FIG. 3 sothat air will enter the compartment area 36 through the air intake openings 98 around the upper periphery of the umbrella portion 44. The vacuum pressure or suction in compartment 36 will draw the fuel from the interior of bowl 20 inwardly through the passageways 72, upwardly through passageway 70 in valve seat insert 68, around the lower end of needle valve 60, into passageways 54 and into the compartment area 36. The gas being sucked from the passageways 54 will mix with the air rushing downwardly over the periphery of umbrella portion 44 and the mixture will be deflected by the surface 132 into opening 134, interior 136 and into the intake manifold of the engine. It can be appreciated that when the accelerator is moved downwardly to open the butterfly valve 140, greater suction or manifold pressure will be exerted in the bore 18 which will cause the throttle valve 22 to be moved further downwardly with respect to the needle valve 60 which permits a larger volume of gas or fuel to be drawn upwardly through passageway 70 since the insert valve seat 68 has been moved further downwardly with respect to the lower end of the needle valve 60 which creates a larger effective opening in the passageway 70.

The idle engine speed may be varied by simply rotating the knob 118 which will raise or lower the needle valve 60 with respect to the valve seat insert 68. When it is desired to enrich the gas-air mixture, it is simply necessary to choke the carburetor by activating the choke wire connected to lever 110 which causes pin 106 to be rotated as previously described so that the needle valve 60 will be raised with respect to the valve seat insert 68 to permit a larger volume of gas to be added to the gas-air mixture.

From the foregoing, it can be appreciated that the throttle valve 22 is controlled by a minus pressure below the carburetor bowl. When the throttle valve is in an up position, the compartment area 36 is substantially closed to the outside atmosphere and as it progressively lowers, the communication between the compartment area 36 and the outside atmosphere progressively increases. The action of the throttle valve and its tapered valve seat insert with respect to the needle valve automatically compensates for varying engine speeds and atmospheric conditions.

The carburetor of FlGS. l-4 not only is a refinement and improvement of those patents identified earlier in the application but is also more economical of manufacture than those previously discussed. The carburetor of HO. 5 functions substantially similar to the carburetor of FIGS. 1-4 with the primary difference being in the location of the fuel bowl. As seen in FIG. 5, the fuel bowl is not affixed to the throttle valve but is provided by the bore 118 in the housing. When valve 170 is opened by the accelerator, suction is applied to the under side of the throttle valve in bore to move the throttle valve 158 downwardly in the bore 155 which causes the tapered valve seat 194 to move downwardly with respect to the needle valve 200 to increase the effective opening between the valve seat 194 and the needle valve so that additional fuel may be drawn therethrough. The fuel is drawn upwardly through passageway 188 and into the valve seat 194 and thence downwardly into the passageway 192 and into the compartment area 164 and thence into the intake manifold of the engine.

The knob 198 may be rotated with respect to the lever 196 to vary the relationship of the lower end of the needle valve 200 with respect to the valve seat insert 194. Rotation of the lever 196 by a choke wire connected to linkage 206 causes the lever 196 to be threadably moved upwardly with respect to cap 195 so that needle valve 200 will be raised with respect to the valve seat insert 194 to permit additional fuel to pass ther'ethrough. The area 214 serves as an acceleration chamber so that the air therein may be drawn outwardly through metering hole 212 when the accelerator is rapidly depressed so that the throttle valve 158 will quickly move downwardly to ensure quick response to acceleration demands.

From the foregoing it can be appreciated that a unique carburetor has been described which permits the same to automatically adjust to varying conditions of atmosphere and various engine speeds. The carburetors as described herein permit idle speeds to be finely adjusted and provide a unique means for enriching the gas-air ratio as needed. The carburetors of this invention eliminate the need for constant manual adjustment of the same when various atmospheric conditions are encountered. Additionally, the carburetors disclosed herein are durable in use and are economical of manufacture. Thus it can be seen that the carburetors accomplish at least all of their stated objectives.

lclaim: v

1. In a carburetor for internal combustion engines:

a carburetor housing means having a compartment area adapted to be in communication with the intake manifold of an internal combustion engine;

said compartment area having an entrance opening formed therein at its upper end;

a throttle valve means slidably mounted in said housing means and adapted to variably restrict the entrance opening to said compartment area;

said throttle valve means having a combustible fluid passageway;

a needle valve stem extending into the passageway of said throttle valve means;

said throttle valve means having at least one fluid exit passageway with one end operatively connected to the said passageway of said throttle valve means and its other end communicating with the inside of the compartment area of said housing means;

said housing means having an air inlet means extending thereinto above the entrance to said compartment area and in communication therewith;

a fluid bowl means in said housing means;

a first conduit having one end communicating with the inside of said bowl means and its other end adapted to be in communication with a source of combustible fuel;

said housing means having a bore means therein below said compartment area;

said throttle valve means being operatively slidably mounted in said bore means;

a second conduit having one end communicating with said compartment area and its other end communicating with the inside of said bore means;

a valve means imposed in said second conduit;

said passageway of said throttle valve means having a valve seat means therein, said valve seat means having a tapered seat portion; and

said needle valve means having an elongated cylindrical end portion which is receivable by the tapered seat portion to variably restrict the flow of fuel therethrough.

2. The carburetor of claim 1 wherein said valve seat means is an insert positioned in said passageway.

3. The carburetor of claim 1 wherein said fluid bowl means is detachably secured to said throttle valve means for movement therewith, said fluid bowl means being slidably mounted in said bore means, said second conduit communicating with said bore means below said fluid bowl means.

4. The carburetor of claim 1 wherein said housing means includes a hollow cylindrical neck portion at its upper end, a collar embracing said neck portion, a cylinder vertically movabl mounted in said neck portion, said needle valve means elng operatively secured to said cylinder for movement therewith, and means connected to said cylinder for vertically moving the same to vary the relationship of said needle valve with respect to said valve seat.

5. The carburetor of claim 4 wherein an idle adjustment knob is threadably mounted in said cylinder, said needle valve means being operatively connected to said knob so that threadable rotation of said knob in said cylinder will vertically move said needle valve means with respect to said valve seat.

6. The carburetor of claim 5 wherein said needle valve means is vertically movably mounted in said knob, said knob having a spring means thereon engaging said needle valve means to yieldably resist the upward vertical movement of said needle valve means away from said valve seat.

7. The carburetor of claim 1 wherein said housing means has a fuel deflecting surface at the upper end of said compartment area adapted to deflect the fuel being discharged from said throttle valve means into the intake manifold of the engme.

E. The carburetor of claim 1 wherein said housing means includes a hollow cylindrical upper end portion defining said fuel bowl means, a cap means closing the upper end of said hollow cylindrical upper end portion of said housing means, a lever means threadably mounted in said cap means, said needle valve means operatively connected to said lever means, and extending downwardly therethrough, and means connected to said lever means for threadably rotating the same in said cap means to vertically move said needle valve means with respect to said valve seat means.

9. The carburetor of claim 8 wherein an idle adjustment knob is threadably mounted in said lever means, said needle valve means being operatively connected to said knob so that said knob can be threadably moved to vary the relationship of said needle valve means with respect to said valve seat means.

110. The carburetor of claim 9 wherein said housing means has a centrally disposed upstanding neck portion in said fuel bowl means which slidably receives the upper end portion of said throttle valve means, said throttle valve means having a sleeve means secured to its upper end portion which slidably extends downwardly around said neck portion, said sleeve means having a fuel passageway formed therein which is in communication with said fuel bowl means and said valve seat means. 

1. In a carburetor for internal combustion engines: a carburetor housing means having a compartment area adapted to be in communication with the intake manifold of an internal combustion engine; said compartment area having an entrance opening formed therein at its upper end; a throttle valve means slidably mounted in said housing means and adapted to variably restrict the entrance opening to said compartment area; said throttle valve means having a combustible fluid passageway; a needle valve stem extending into the passageway of said throttle valve means; said throttle valve means having at least one fluid exit passageway with one end operatively connected to the said passageway of said throttle valve means and its other end communicating with the inside of the compartment area of said housing means; said housing means having an air inlet means extending thereinto above the entrance to said compartment area and in communication therewith; a fluid bowl means in said housing means; a first conduit having one end communicating with the inside of said bowl means and its other end adapted to be in communication with a source of combustible fuel; said housing means having a bore means therein below said compartment area; said throttle valve means being operatively slidably mounted in said bore means; a second conduit having one end communicating with said compartment area and its other end communicating with the inside of said bore means; a valve means imposed in said second conduit; said passageway of said throttle valve means having a valve seat means therein, said valve seat means having a tapered seat portion; and said needle valve means having an elongated cylindrical end portion which is receivable by the tapered seat portion to variably restrict the flow of fuel therethrough.
 2. The carburetor of claim 1 wherein said valve seat means is an insert positioned in said passageway.
 3. The carburetor of claim 1 wherein said fluid bowl means is detachably secured to said throttle valve means for movement therewith, said fluid bowl means being slidably mounted in said bore means, said second conduit communicating with said bore means below said fluid bowl means.
 4. The carburetor of claim 1 wherein said housing means includes a hollow cylindrical neck portion at its upper end, a collar embracing said neck portion, a cylinder vertically movably mounted in said neck portion, said needle valve means being operatively secured to said cylinder for movement therewith, and means connected to said cylinder for vertically moving the same to vary the relationship of said needle valve with respect to said valve seat.
 5. The carburetor of claim 4 wherein an idle adjustment knob is threadably mounted in said cylinder, said needle valve means being operatively connected to said knob so that threadable rotation of said knob in said cylinder will vertically move said needle valve means with respect to said valve seat.
 6. The carburetor of claim 5 wherein said needle valve means is vertically movably mounted in said knob, said knob having a spring means thereon engaging said needle valve means to yieldably resist the upward vertical movement of said needle valve means away from said valve seat.
 7. The carburetor of claim 1 wherein said housing means has a fuel deflecting surface at the upper end of said compartment area adapted to deflect the fuel being discharged from said throttle valve means into the intake manifold of the engine.
 8. The carburetor of claim 1 wherein said housing means includes a hollow cylindrical upper end portion defining said fuel bowl means, a cap means closing the upper end of said hollow cylindrical upper end portion of said housing means, a lever means threadably mounted in said cap means, said needle valve means operatively connected to said lever means, and extending downwardly therethrough, and means connected to said lever means for threadably rotating the same in said cap means to vertically move said needle valve means with respect to said valve seat means.
 9. The carburetor of claim 8 wherein an idle adjustment knob is threadably mounted in said lever means, said needle valve means being operatively connected to said knob so that said knob can be threadably moved to vary the relationship of said needle valve means with respect to said valve seat means.
 10. The carburetor of claim 9 wherein said housing means has a centrally disposed upstanding neck portion in said fuel bowl means which slidably receives the upper end portion of said throttle valve means, said throttle valve means having a sleeve means secured to its upper end portion which slidably extends downwardly around said neck portion, said sleeve means having a fuel passageway formed therein which is in communication with said fuel bowl means and said valve seat means. 